We tried to study on the possibility to apply the dichloromethane (DCM)-degrading bacteria as bioreactor in order to decompose the DCM used in manufacturing process.
Using the samples that collected at 16 places in the environment, the isolation of DCM-degrading bacteria was performed in the media in which included DCM as the single carbon source. Consequently, 14 bacterial strains with high DCM- degrading ability were observed. As a results of identification based on 16S-rDNA gene analyses, all of these strains were identified as Hyphomicrobium sp. belonging to the group "methylotroph". The small experimental apparatus was designed and it was filled with DCM-degrading bacteria adhered on the polypropylene support plates. Using the closed system apparatus and representative bacteria strain, S-1, DCM degradable ability was evaluated in the circulation of DCM aqueous solution supplemented with the nutrient salts. In consequence, DCM solution was completely degraded up to 500 mg/l DCM concentration in 10hours and it showed good degradable ability corresponding ca 1mg/unit/h. In addition, we confirmed that DCM in the manufacturing waste solution (e.g. seal water from vacuum pump, extracted aqueous layer) was also degradated in this apparatus similarly, without any problem.
Furthermore, it was confirmed that in the coexistence of other bacteria than Hyphomicrobium sp. degradation of DCM was performed similarly as in Hyphomicrobium sp. alone, if DCM is supplied sufficiently.
This study showed the promising results concerning to the application of bioreactor to degrade DCM by using the isolated bacteria.